FORT CARSON, Colo. -- Miles of power lines crisscross Fort Carson's 137,000 acres, providing essential electricity to the garrison, but the many poles present a deadly threat to wildlife, especially raptors.
Raptors are at greater risk, in part because of their wide wingspan, but also because of their predatory nature. Although most raptors hunt from the air, some species prefer to engage in a "still hunting" technique from a high vantage point, thereby saving the energy required for flight. Power poles provide ideal perching, hunting and nesting opportunities, especially in open areas where natural perches are limited.
Nationally from 1960-1995, more than 4,300 eagle deaths from power lines were reported, and the greatest number of fatalities occurred in open prairie landscapes, similar to those found around Fort Carson. Since these numbers only account for the deaths that were both noted and reported, the actual number killed is likely much higher. Most avian mortalities go unnoticed, particularly in remote areas where power lines are not inspected frequently and fallen birds are quickly consumed by scavengers.
Occasionally, birds are not killed instantly, but are gravely injured, suffer and die days later far from the pole. In addition to the negative impact that these fatalities have on the raptor population, wildfires can be ignited when an electrocuted bird catches on fire and falls to the ground and power companies are inconvenienced by the temporary power outages and line trips.
Power lines on Fort Carson have been evaluated for potential raptor electrocution risk, based primarily on evidence -- quantity of whitewash, bones from prey and visual observations -- that indicate high raptor use and on pole configuration. A second inventory is currently under way at Piñon Canyon Maneuver Site, a 200,000 noncontiguous maneuver site located 150 miles southeast of Fort Carson. Although the landscapes and levels of military use are different, the same criteria are being used for both evaluations. Of the 1,113 poles evaluated at Fort Carson, 59 demonstrated heavy use, and of those, 13 were deemed critical and in need of immediate attention.
"Fort Carson is dedicated to preventing raptor fatalities from power lines," said Carlos Rivero-deAguilar, Fort Carson Directorate of Public Works Environmental Division chief. "Since funding is not available to retrofit every single power line, the first phase in the raptor protection effort is to evaluate and prioritize the existing poles within the garrison boundary."
DPW biologists are partnering with local electric companies to implement some of the avian protection techniques outlined in Avian Protection Plan, a document which power companies and U.S. Fish and Wildlife Service partnered to prepare. Understanding raptor behavior and the mechanics of how raptor electrocution occurs are essential steps in the implementation of effective protection techniques.
Birds are not injured by voltage alone. They must simultaneously complete the circuit between two energized points (lines or conductors) or between an energized line and a ground.
Many raptors have a substantial wing span and may accidentally hit both energized lines with their wings during landing and takeoff. Tall water birds, like great blue herons, are also at risk because of their vertical height and the probability that their feathers are wet and therefore more conductive. Although the raptors' wingspan and the spacing of live wires are the primary electrocution risk factors, high-use poles with complicated configurations (multiple energized and grounded metal parts), proximity to a food source, age of the bird, availability of alternative perches, inclement weather, breeding seasons and nearness to a migratory pathway play a role.
Remedial actions outlined in the APP include expanding the horizontal length of the cross arm from 8 to10 feet or providing at least 60 inches of clearance between live wire and points to decrease the likelihood that large raptors can contact both lines and points simultaneously when they flap their wings. Other protection measures include increasing the vertical spacing between energized and ground wires, and placing insulating rubber covers over exposed wires, jumpers and conductors to protect a bird in the event of accidental contact. Another effective and simple retrofit is to erect an alternate perch several feet above the live wires.
In February, Fort Carson opted to install protective rubber covers over the exposed wires and components on 13 of the highest risk poles. On select poles, the neutral wires may be lowered to increase the vertical separation between the live and ground wires. Fort Carson biologists will be collaborating with local power companies to retrofit additional hazardous power poles; however, funding is essential.
"What we have worked on to date at Fort Carson is 13 critical poles owned by the government," said Alan Davis, DPW Operations and Maintenance Division electrical engineer and technician. DPW coordinated with its operations and maintenance contractor, Fort Carson Support Services, to have the work done. Additional frequently used poles may be modified in future.
From a compliance and cost standpoint, it is imperative that Fort Carson and the electrical companies mitigate hazardous poles, since there are grave legal repercussions imposed for any raptor mortalities, intentional or not.
The Bald Eagle Protection Act, enacted in 1940, and later amended to include golden eagles, applies criminal and civil penalties to any person who knowingly or unintentionally "take, possess, sell, purchase, barter, offer to sell, purchase or barter, transport, export or import, at any time or any manner, any bald (or golden eagle), alive or dead, or any part, nest or egg thereof." The word "take" is defined as to "pursue, shoot, shoot at, poison, wound, kill, capture, trap, collect, molest or disturb."
Penalties for violations are severe and can result in fines of $100,000 -- $200,000 for an organization -- a year in jail, or both. Electrocution of golden or bald eagles falls under the definition of a "take" and is therefore illegal.
In addition to reducing mortality risks from power lines, Fort Carson biologists have initiated several projects to enhance raptor habitat, support raptor protection and monitor raptor populations. They have coordinated with local Boy Scouts to build raptor nest boxes which are installed throughout the garrison, with the exception of air fields and high traffic areas, where raptor activity is intentionally discouraged to prevent accidental collisions.
Biologists are collaborating with San Isabel Electric, a Colorado utility company, which has indicated willingness to install several alternate perch poles in critical areas at PCMS. During the winter, surveys for migratory raptor species are conducted and golden eagle nests are monitored so that buffers can be placed around active nests to ensure the eagles are not disturbed while nesting.
All these efforts are being supported by Fort Carson to preserve and protect these important species for the health of the environment and the enjoyment of future generations.
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